1. Field of the Invention
The present invention relates generally to means for correcting angular misalignment of the output from a diode laser array upon collimation, and more particularly to a computer-generated alignment grating corrector array which corrects the directional errors of the individual diodes of the diode laser array.
2. Brief Description of the Prior Art
Many current laser applications require a source of high power, highly coherent laser radiation. This source is typically a diode laser array in which multiple linear laser diode arrays are stacked to produce a compact, two-dimensional laser diode array. During the fabrication of such diode laser arrays, however, manufacturing errors may produce linear arrays which exhibit non-linear "bowing" such that the diodes are no longer horizontally aligned. The non-linear "bowing" of the laser diode array introduces an angular misalignment of the individual diodes upon collimation.
The angular misalignment is due to the differences in the vertical positioning of the output beams of the individual laser diodes as they are collimated. For example, a linear laser array with a substantially horizontal output that does not suffer from non-linear "bowing" will produce a series of output beams that will propagate in a substantially horizontal plane from the emitting facets of the laser array through the collimating lens. In contrast, laser diodes within the same exemplary laser array that are "bowed" or misaligned will produce output beams that will be positioned above or below horizontal and upon collimation will remain angularly misaligned with respect to the substantially horizontal plane.
These directional errors of a non-linear "bowed" diode laser array may be corrected by individually fabricated microprism arrays in which individual prisms are placed in each diode's path. Each prism must then be positioned such that there is no angular misalignment upon collimation. The use of microprism arrays in this application is extremely labor intensive and therefore cost prohibitive. Microprism arrays also tend to be fragile and to delaminate with time and temperature cycling.
It would thus be desirable to develop a correcting array for such non-linear "bowed" diode laser arrays which may be constructed from simple fabrication steps so as to be inexpensive. Furthermore, it would be desirable for the correcting array to be long-lasting and capable of withstanding wide variations in temperature without degradation.